PROCEEDINGS 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. XII, No. i, pp. 1-25. Pl. i, Figs. 1-7 February 15, 1910. 



ON THE MANNER OF LOCOMOTION OF THE DINO- 

 SAURS ESPECIALLY DIPLODOCUS, WITH REMARKS 

 ON THE ORIGIN OF THE BIRDS. 



By Oliver P. Hay. 



In a paper published some months ago (Amer. Naturalist, vol. xliii, 

 1908, pp. 672-681) the writer advanced the proposition that thesauro- 

 podous dinosaurs, especially Diplodocus, did not walk, as the elephants 

 do, with the body high up from the ground and with the legs straight 

 or nearly so, and moving in approximately perpendicular planes, but 

 rather as do the crocodiles, with the body low down, and with the 

 thighs standing well out from the animal's sides. While I was further 

 considering the subject I received from my friend Dr. O. Abel, of 

 Vienna, a paper' in which, while endorsing my views regarding the 

 nature of the food of Diplodocus and the manner of taking it, he en- 

 deavors to show that I am in error as to the bodily pose and the manner 

 of locomotion of the sauropods. Dr. Abel maintains that the accepted 

 views of the way in which these animals walked is the correct one and 

 he finds support for this view in the structure of the feet. He accepts 

 Hatcher's opinion that Diplodocus and Brontosaurus were digitigrade 

 and argues that therefore they walked as represented in Hatcher's 

 restoration of the reptile. The evidences that they were digitigrade 

 are found in the belief, probably correct, that the upper ends of the 

 metatarsals and metacarpals were not arranged in a straight line, but 



• Verhandl-zool.-botan. Gessellsch. Wien, 1909, pp. 1 17-123. 

 Proc. Wash. Acad. Sci. , February , 19 10. 



